Hot dirt keeps your plants happy in the winter months

[Craig] tried heating his greenhouse last winter, but really only managed to push the limits of his utility bills. This time around he took a different approach by building a system to warm the soil in which his vegetation is planted.

The core of the system is this box which houses the plants. It is lined with heating tape along the bottom which warms a layer of dirt. The plants are in pots, but since those are surrounded by the dirt it doesn’t really inhibit the warming properties of the soil. The controller takes into account the temperature inside the box, as well as ambient temperature in the greenhouse. When it’s a bit too cold the controller will close the lid, which is covered with translucent plastic. This makes sure the temperature around the plants won’t fall below about 41.5 degrees Fahrenheit.

This really takes the work out of caring for you plants in the winter. What would have been a multiple-times-per-day visit can be limited to every day or two. Now he just needs to expand this to regulate temperature and humidity in the greenhouse itself, kind of like this other hack.

This is really impressive and creative. I can appreciate the problem as I did a quick and dirty experiment to warm soil for some herbs. My attempt worked well and I am using the basil tonight. But definitely a low tech experiment. I hesitate to post the link but, interesting how well it can be done in this coffin sized project. http://www.observationsblog.com/3/category/window%20herbs/1.html There is an update listed in the archive under “Herb Update”. My hat is off to you sir! Great work.

I LOVE gardening. It is one of my favorite relaxing things to do (as long as my wife isn’t yelling “the plants are dying” then I’m good.).

With that said, I like the idea of this project. I have an extensive indoor grow cabinet that I have been working on for about 7 years. I am constantly updating it and doing other various improvements.

But for anyone that is serious about grow room controlling (or has a lot of money burning a hole in their pocket), you can check out Growtronix. It is a little expensive, but it is very very useful. In the perfect condition the Growtronix software and hardware can be just right, but for us HackADay folks, we might prefer something that is more direct and less UI garbage. But Growtronix is still worth checking out.

I spent about $1,200 on their software/hardware 7 years ago. Unfortunately I barely use it now, but that is only because the computer I was using for it finally died. :(

If anyone wants to attempt this, you can use a much smaller lid actuator by counter-balancing the lid. This way the actuator only has to overcome the frictional resistance, rather than having to lift the weight of the lid as well.

I don’t want to discourage you in your efforts. But wouldn’t it be much easier to use the old concept of using the rotting of horse dung as an natural thermal source?
In addition you get fine nutrient-rich soil. :)